Concerning a conventional sheet cutter for cutting a soft sheet such as a ceramic green sheet, for example, sheet cutters which are disclosed in the official gazettes of Japanese Unexamined Patent Publication Nos. 2001-113520 and 1-122408 are known. Japanese Unexamined Patent Publication No. 2001-113520 discloses a sheet cutter having the following cutting blade attaching structure. The sheet cutter has one cutting blade which is elevated by one drive section. A cutting blade holder (cutting blade elevating body) to which the cutting blade is attached is fixed to a lower end portion of the guide rod, which is elevatably provided in the frame, in such a manner that the cutting blade holder protrudes downward, and an elevating drive section is connected to a center on an upper face of the cutting blade holder.
Japanese Unexamined Patent Publication No. 1-122408 discloses a sheet cutter having the following cutting blade attaching structure. A base table is provided on a movable table elevated by a feed screw, and a horn (cutting blade elevating body) is attached to the base table in such a manner the horn protrudes downward and one cutting blade is attached to the horn.
As described above, as one cutting blade is elevated by one drive section in the cutter described in Japanese Unexamined Patent Publication No. 2001-113520, in the case where a pair of cutting blade elevating bodies are provided, it is necessary to provide a pair of guide rods and it is also necessary to provide a pair of drive sections. Accordingly, problems may be caused in which the structure of the cutting blade elevating section becomes complicated and the size of the cutting blade elevating section is extended.
In addition, as a pair of guide rods are elevatably arranged in the frame and the cutting blade elevating body is attached to a lower end portion of the guide rod in such a manner that the cutting blade elevating body protrudes downward, the cutting blade elevating body is liable to be deformed or tilted. Therefore, the cutting accuracy of the sheet cutter is lowered.
In the case of Japanese Unexamined Patent Publication No. 1-122408, the following problems may be encountered. The base table is arranged on the movable table elevated by the feed screw, and the horn is attached to the base table in such a manner that the horn protrudes downward. Thus, in the case where a pair of cutting blades are provided, it is necessary to have a pair of feed screws and it is also necessary to have a pair of movable tables. Therefore, the structure becomes complicated and the size of the sheet cutter is extended. Further, the horn to hold the cutting blade is liable to be tilted. Accordingly, the cutting accuracy is lowered.
The present invention has been accomplished to solve the above problems of the prior art. It is an object of the present invention to provide a sheet cutter in which the cutting blade elevating section is downsized; the cutting accuracy is high; and the cutting speed is increased, even if the sheet cutter cuts a sheet, so as to have different cutting lengths, with two cutting blades.